Besieging Snowball

A swirling, stormy, ball of ice and snow launches forward from you in a straight line. The ball begins as a small object, dealing 4d8 cold damage and 4d8 bludgeoning damage in a 20-foot radius from its edge upon impact. A creature struck or engulfed by the ball or caught within this radius may attempt a Constitution saving throw when it explodes, taking half damage on a success. It travels 120 feet per round, exploding after 3 rounds or when it hits a creature or object larger than itself.

After the ball travels 30 feet, it becomes a medium object 5-feet wide, and the damage it would deal increases by 4d8 cold and 4d8 bludgeoning (to a total of 8d8 cold and 8d8 bludgeoning). For every additional 30 feet, the ball travels its size increases by 5 feet, and the damage it would deal increases by an additional 4d8 cold and 4d8 bludgeoning.

Creatures and objects equal to or smaller than the ball's size must succeed a Strength saving throw equal to your spell save DC or become magically engulfed by the ball, traveling with it until it explodes. On a success, they are not engulfed and take half the damage the ball would currently inflict upon impact. After the ball explodes, an engulfed creature or object is dropped in the nearest empty space.